AA batteries power devices such as headlamps, digital cameras, and battery-operated screwdrivers. These 1.5V batteries have a nominal diameter of 14mm.

AAA batteries power small devices like remote controls. These 1.5V batteries have a nominal diameter of 11mm.

C batteries power mid-sized devices such as flashlights and small portable radios. These 1.5V batteries have a nominal diameter of 26mm.

9V batteries power devices such as smoke alarms, carbon monoxide detectors, clocks, and walkie-talkies. They are sometimes called smoke-alarm batteries.